Actuating device for loud speakers



May 29, 1928. v

-' c. L. FARRAND ET AL ACTUATING DEVICE FOR LOUD SPEAKERS Filed June 23, 1927 2 SheetsSheet 1 BY M MT? ATT MQS May 29, 1928. 1,671,105

C. L. FARRAND ET AL ACTUATING DEVICE FOR LOUD SPEAKERS Filed June 23, 1927 2 Sheets-Sheet 2 BY W "RTTORNEY S hatentcd liiiay 29,

UNITED STATES 1,671,105 PATENT OFFICE.

CLAIR L. FARRAND, OF FOREST HILLS, NEW YORK; ERNEST ROSS, OF EAST ORANGE, INF-EV JERSEY; AND ALBERT D. SILVA, OF FOREST HILLS, NEW YORK; SAID 3088 AND SAID SILVA ASSIGNORS TO FARRAND MFG. CO. INC., 01 LONG ISLAND CITY, NEW YORK, A COBPGRATION OF NEW JERSEY.

ACTUATING DEVICE FOR LOUD SPEAKERS.

Application filed June 23,

This invention relates to electromagnetic actuating devices for radio loud speakers and the like.

One object of the invention is to provide an improved armature assembly for elec' tromagnetic actuating devices and an improved electromagnetic actuating device embodying that assembly.

Another object of the invention is to provide an improved electromagnetic actuating device which is compact and inexpensive to manufacture.

A further object is to provide an electromagnetic actuating device having improved means for holding the pole pieces in fixed relation withrespect to each other.

The improved armature assembly and a complete electromagnetic actuating device embodying the armature assembly are illus trated in the accompanying drawings in which:

Fig. 1 is a perspective view of the parts of the armature assembly before they are assembled Fig. 2 is a perspective view of the com pleted armature assembly;

Fig. 3 is a longitudinal section through the armature assembly taken on the line 33 of Fig. 2. In this figure, however, a speech coil has been added which is not shown in Fig. 2;

Fig. 4 is a perspective view showing all of the parts of the actuating device except the permanent magnet, the parts being shown in proper relative positions but slightly separated to show how they fit together;

Fig. 5 shows the parts illustrated in Fig. 4 clamped together into a complete unit;

Fig. 6 is'a transverse section through the assembled unit shown in Fig. 5. the section being taken on the line 66 of-Fig. 5;

Fig. 7 is a front elevation of a complete actuating device showing how the unit of Fig. 5' may be applied to the permanent magnet; a

Fig. 8 is a top plan view of the actuating device shown in Fig.7; and

- Fig. .9 is a horizontal section taken on the line 9-9 of Fig. 7.

As shown in Fig. 1 the parts of the armature assembly include two sheet metal'channel shaped members 1 and 2 each of which 1927. Serial No. 200,814.

has a bottom wall 3 and side flanges 4. The bottom wall 3 of each channel shaped member has integral end portions 5 which extend longitudinally beyond the flanges 4 for the purpose hereinafter described.

The parts of the armature assembly also include sheet metal flanges 6 and 7 having central rectangular openings 8. The armature is shown at 9. It has solderedto-it a rod 10 which constitutes part of the connections to the diaphragm.

The bottom wall 3 of each channel shaped member has an indentation 11 which forms an inwardly extending projection 12. Each side wall of the armature 9 is provided with an indentation 13.

Then the parts shown in Fig. 1 are assembled the channel shaped members 1 and 2 are positioned against the armature so that the projections 12 on the channel shaped members engage in the indentations on the'armature. The flanges 6 and 7 are then slipped over the ends of the channel shaped members in such a Way that the end portions 5 extend beyond the flange members. The parts are held in this position and soldered together to form the complete unit shown in Fig. 2. From this figure it will be seen that the flange members 6 and '7 together with the channel shaped members 1 and 2 form a spool or bobbin for the speech coil. The channel shaped members 1 and 2 in conjunctionform a hollow core for the bobbin and the armature -9 extends through the hollow core, the indentations 13 on the armature and the projections 12 on the channel members serving as a pivotal support for the armature as shown in Fig. 3. I

The extensions 5, measured in the direction' of vibration of the armature, are wider than the ends of the armature so that they act as spacing means for the pole pieces when the armature assembly is combined witlrthe other parts of the device.

The spool or bobbin shown in Fig. 2 is wound witha coil of wire represented at 100 14 in Fig. 3.

Fig. 4 shows the manner in which the ar mature assembly and the speech coil are combined with all of the other parts of the v actuating device except the magnet. These 104;

Each poie piece may be a fiat strip of metal having its end a U-shaped opening 2.? which forms on each pole piece two poles l8 and 19. 'The'pole pieces may, if desired, be one strip of metal, but in the present instance they are composite, each pole piece comprising two juxtaposed strips of metal similarly formed. The parts shown in "Fig. 4; include two sheet metal channel shaped members 20 and 21 which act as clamps to hold the pole pieces rigidly ,in position when the parts are assembled. There is also shown in Fig. at a terminal board 22 made of insulating'material having a pair of terminals 23 secured to it to which the leads from the radio set may be connected. These terminals are connected with clips 23 to which the ends of the speech coil ma be soldered. A spring member 24 to whic 1 is soldered a rod 25 completes the parts shown in Fig. 4.

When the parts shown in Fig. 4 are assembled and clam ed together they form the unit shown in ig. 5. All of the parts shown in Fig. 4 are provided with openings which are adapted to register when the parts 'areassembled so that bolts 26 and 27 may be passed through them to clamp the parts together. When so clamped together the two poles on one pole piece overlap with respect to the corresponding poles on the other pole piece to form two air gaps in which the ends of the armature are located. The extensions 5 on the channel shaped members 1 and 2 are clamped between the pole pieces and act as definite spacing means for the poles so that the size of the air gaps is predetermined. It is only necessary to clamp the pole pieces against the extensions 5 without the necessity of careful adjustment or regulation of the air gaps because the size of the air gaps is definitely fixed by the spacers -5.

The side flangesof the clamping member 20 are relatively deep at one end as shown at 26 so that they extend to the pole piece 16 and are relatively shallow at the other end as shown at 27 so that they project over and extend to the pole piece 15. Likewise, the side flanges of the clamping member 21 are relatively deep at 28 so as to extend to the pole piece 15 and are relatively shallow at 29 to project over and extend to the pole piece 16. The outer member at one side of the unit shown in Fig. 5 is the terminal board 22, and the outer member at the other side of the unit is the spring 24. The spring 24:.is adapted to be connected with the rod 10 on the armature 9, but the connection is not made until after all of the parts are clamped together. After the parts are clamped together the armature is held in its central position, as by inserting a thin strip of metal in the gap at each side of the armature, and then the rod 10 is soldered to the menace the sizes of all the gaps between the ends oi the armature and the poles will be the same.

The outer ends of the pole pieces 15 and 16 are provided with openings 30 and 31 so that the projecting ends of the pole pieces may be bolted directly to the extremities of a U-shaped magnet 32 as shown at 33 and 34 in Fig. 7. As the outer ends of the pole pieces do not lie in the same plane it is necessary to insert between one pole piece and the corresponding leg of the magnet one or more metallic washers shown at 35 in Figs. 8 and 9.

The armature is preferably made of 40% nickel steel and the pole pieces are preferably made of 4% silicon steel. The channel shaped members 1 and 2, and flange members 6 and 7 of the spool or bobbin may be made of brass and the clamping members 20 and 21 may also be made of brass.

The actuating device was especially designed for use in radio loud speakers of the cone type, but it may be used for actuating any kind of a diaphragm or as an actuating device in general. \Vhen used as an actuating device for a radio loud speaker it may be mounted in any suitable way with respect to the diaphragm. The rod 25 is connected with the diaphragm. In the case of a cone type speaker it is connected with the apex of the cone. The vibrations of the armature 9 are transmitted by the rod 10 to the spring 24. The rod 25 transmits the vibrations from the spring 24 to the diaphragm.

The actuatingdevice herein disclosed is inexpensive to manufacture as nearly all of its parts may be made of stamped metal. Only a few parts are required and theconstruction is extremely compact as will be apparent, especially from Fig. 5.

Inasmuch as the armature is centrally mounted with respect to the channel shaped members 1 and 2, and inasmuch as the extensions 5 on the channel shaped members, measured in the direction of vibration of the armature, are'wider than the ends of the armature the pole pieces may be quickly clamped in place without giving any thought to the size of the air gap because idly in position.

e claim:

1. An armature assembly for electromagnetic actuating devices comprising an armature, and at least one sheet metal member to which the armature is pivoted, an integral portion of said sheet metal member being tive means for holding the pole pieces rigarranged laterally beside an end portion of to which it is pivoted, said side member having integral end portions arranged laterally of the ends of the armature and ot greater width measured in the direction 0:

' vibration ot' the armature'than the ends of the armature whereby they may act as spacing means for pole pieces.

3. An armature assembly for electromagnetic actuating devices comprising an armature, a sheet metal side member located at each side of the armature, means for holding said side members in fixed position with respect to each other, a pivotal connection between the side members and the armature,

said side members having integral end por tions arranged laterally of the ends of the armature, the end portions of said side members measured in the direction of vibration of the armature being of greater width than the end portions of the armature for the purpose described.

4. An armature assembly for electromagnetic actuating devices comprising an armature, a sheet metal hollow 'core in which the armature is pivoted, and flange members to which the hollow core is secured and forming with the core a bobbin for a coil of wire, said core having integral end portions projecting beyond the side flanges and arranged laterally of the ends of the armature, said end portions of the core measured in the direction of vibration of the armature being wider than the ends of the armature Whereby said end portions of the core may serve as spacing means for pole pieces.

5. An armature assembly for electromagnetic actuating devices comprising an annature, a sheet metal channel shaped member located at each side of thearmature and forming in conjunction a hollow bobbin core, means. for pivotally supporting the armature in said core, and flange members to which the channel members are secured and forming with said core a bobbin for a coil of wire, sai d channel members having end portions projecting beyond said flanges ends of the armature whereby said end portions of the channel members may serve as spacing means for pole pieces.

6. An armature assembly for electromagnetic actuating devices comprising an armature, a sheet metal channel shaped member located at each side of the armature and forming in conjunction a hollow bobbin core, each channel shaped member having an indentation forming an inwardly extending projection, and the armature having indentations to receive said projections whereby the armature is pivoted to vibrate be tween the channel members, and flange members to which the channel members are socured and forming with said core a bobbin for a coil of wire, said channel members having end portions projecting beyond said flanges and arranged laterally of the. ends. of the armature, said end portions of the channel members measured in the direction of vibration of the armature being wider than the ends of the armature whereby said end portions of the channel members may serve as spacing means for pole pieces.

7. An armature assembly for electromag netic actuating devices comprising a bobbin havin a sheet metal hollow core and end said core, said core having indentations forming inwardly extending projections and said armature having indentations to receive said projections whereby the armature is pivotally mounted within the core.

8. .An armature assembly for electromag netic actuating devices comprising an armature support formed of sheet metal, and an armature associated with said support, the sheet metal support having indentations forming inwardly extending projections and the armature having indentations to receive said projections whereby the armature is pivotally mounted on the support.

9. An armature assembly for an electromagnetic actuating device comprising an ar mature support and an armature associated with said support, said support having inwardly extending projections and the armature having recesses to receive said projections whereby the armature is pivotally mounted on said support.

10. An actuating device for loud speakers comprising a magnetic field structure. having a pair of poles, an armature an end of which .is located between said poles, at least one sheet metal member to which the armature is pivoted, an integral portion of said sheet direction of vibration of the armature being I z .wider than the (11d of the armature whereby the end portion of said member serves as spacin means for. said poles:

11.. n actuating device for, loud speakers comprising i a niag'ntio 'ufield structure hav-.

ing two pairs of poles, an armature each end of which is located between the two poles of one pair, a hollow sheet metal core structure in which the armature is pivoted interme diate its ends, said sheet metal core structure having end portions each, of which extends between the two poles ofone pair,.

and means, for clamping said portions between the poles, said end portions of the core structure measured in the direction ot vibration: of the farmiiture being wider than .the end portions *of the armature whereby 'sa'id end portions ofthe core structure serve as spacing means for the p'oles.

12. An actuating device for loudspeakers comprising a fmagnetic field structure haviiig two pairs of poles,-an armature each -end ofwhich is located between the two'poles of one pair, a channel shaped member located at each side ofthe-ariiia't ire, end flanges t'o which said channel, shaped members are secured therebyforminga bobbin with a hollow core] in which the armature is locateda-speech coil on said bobbin, said channel vshaped members having integral extensions.

positioned between the poles, means for piv otally mounting the armature on said .chan'-' nel shaped side members sothat it is capable of vibrating in said core, and means for clamping the integral extensions of said channel shaped members between the poles,

tures;

said integral extensions of said channel shaped members measured in the direction of vibration of the armature being wider =than the end portions of the armature whereby they serve as spacing means for the poles.

13. An electromagnetic actuating device for loud speakers and'the like comprising a. magnet, substantially fiat pole pieces sepiece and means for clamping said members together with the pole pieces between them.

14. Anhelectromagnetic actuating device for loud speakers and the like comprising a magnet, substantially fiat pole pieces secured ping relation, means for holding the pole pieces in fixed pOSlUOItStIId means comprising a pair of channelshape'd members liavthereto the ends of which are in overla'ping cut out portions in their side walls so .i

that eaclrmember has relatively deep flanges at one end extending to one pole piece and" relatively shallow flanges at the other end projecting over and extending to the other "pole piece, and means for clamping said members together with the pole pieces between them.

In testimony whereofwe aifix our signa- CLAIR L. FARRAN-D. ERNEST ROSS. ALBERT D. SILVA. 

